I've no idea, but it must have something to do with Friction. Air??? so as it moves, a tiny fraction of air resistance has to be removed?? Purely a guess.

It's great! ..but after a set period of the Ghosts heading in their pre-planned route, they should then head towards Pacman when he is in sight! Makes the game far more exciting.

Looking great.. Although, the ice elements don't seem to do anything untoward. Surely you should skid the direction you start off in? In the final few screens, some of the disintegrating platform objects are in front of the player. Finally, there is a bug with jumping and collision detection. If you jump into a move block, it sort of freezes with the player and if you hold down jump, the player eventually ends on top!! :)